Patch-making tool



Aug. 8, 1939. DUGAW 2,18,766

PATCH-MAKiNG TOOL Filed June 1, 1936 alien/M4113 Patented Aug. 8, 1939 UNITED STATES PATENT OFFIQE 7 Claims.

This invention relates to woodworking tools for making patches adapted to be applied to veneer, plywood panels, or wood boards to fill a cut-out space therein from which a pitch pocket, knot, or other defect in the wood of the panel has been removed.

The knives herein described may be used either in connection with a suitable machine, or as hand tools for the said purpose. With slight modifications the machine and the knives may be used for cutting the hole in the board, plywood panel, or veneer sheet, into which the patch is to be inserted.

Many attempts have been made to out these patches by machinery, but the methods heretofore in use have been too slow, too inconvenient for practical use, too costly, or they have produced poor results, thus lowering the grade and salability of the manufactured product. In particu- 20 lar, punches of various types have been used, and

some are still in use, but their use has been practically confined to the lower grades of plywood because the patches made by them are, as a rule, not as good as the hand-chisel method, still in 25 most common use. In this usual hand-chisel method, one side of the patch is first cut and then the tool is turned, gaged and struck to cut out the patch. The same operation is performed to cut the hole into which the patch is to be inserted. The above-mentioned punches lose their shape by sharpening, and break down the tips or points of the patch and, on account of the fact that they are made tapered, they cut a larger patch after being resharpened, thus requiring either a new 3 punch or a larger chisel to cut the hole into which the patch fits. The said punches also have a tendency to make a straight or unbeveled cut through the wood. The cost of upkeep on the tools used in the above described punch method 40 soon offsets any saving in time gained in the work of patching, while in my invention in which two separate cutting knives are used in conjunction with each other, the one forming a guide or gage 45 for the other, whether used by hand or in a machine, operate much faster and perform a higher grade of work, and need less attention, and the patch made thereby fits more perfectly into the hole, especially at the points, thus forming a per- 50 feet patch and raising the quality of the product as well as saving in the cost of labor.

It is a general object of my invention to provide a means whereby the speed of operation of cutting patches is greatly increased, thereby cutting down the cost of the individual patches; and to produce greatly improved patches, thereby enhancing the value of the patched piece.

It is an object of my invention to provide a means for cutting the patch, which will be of the same size and shape independent of the amount which has been ground off therefrom in sharpening; which may be easily maintained in sharpened condition; which will leave a slight tail or sliver at each end of the patch piece; which will cut a patch in one stroke and yet pr0- duce a patch with beveled sides.

I attain these and other objects by the devices, mechanisms, and arrangements, illustrated in the accompanying drawing, in which- Fig. 1 is a plan view of a pair of cutter knives as positioned to cut a patch by hand; Fig. 2 is a side elevation thereof; Fig. 3 is a front elevation thereof, a portion thereof being shown in section; Fig. 4 is a View similar to Fig. 3, showing the ends of the cutter knives at the end of the cutting stroke, to illustrate in somewhat exaggerated form the spreading of the upper ends under the action of the cutting blow thereon; Fig. 5 is a plan view of one end of a patch as cut by these knives; and Fig. 6 is similar to Fig. 1.

Similar numerals of reference refer to similar parts throughout the several views.

The cutter is formed of two separate, unattached, knives I and 2. Each knife is made of a piece of curved steel, the curve thereof being uniform throughout the length of the knife, and being of the same radius in each knife. However, the edges 3 of such knives are not quite parallel, but the knives are slightly wider at their upper ends 4 than at their cutting edges 5, thus providing a slightly increased space 6 between the knives from the cutting point upward and permitting each patch 1, as' it is cut out from the strip, to pass upward freely in the space 6. The cutting ends 5 of the knives may be slightly 40 curved inward at 8 in order to give the patch 7 a slightly beveled edge throughout its length. One of the knives I may be notched or cut away very slightly at 9 in each of its cutting corners, up to a point about one-half inch above the cutting edge 5, depending somewhat on the size of the patch being out. These notches 9 cause the upper-outer corner thereof to become a fulcrum about which the notched knife I may turn as it is driven into the wood to cut the patch I, thereby slightly increasing the distance between the upper ends of the knives l and 2. These notches 9 also result in a small tail or sliver I!) being formed on each end of the patch 1, as shown in Fig. 5. In this figure the sliver II] is somewhat exaggerated in size and it is to be understood that as the patch 1 rises in the space 6 between the two knives I and 2, the sliver I0 is further trimmed off by the sharpened edge ll of the notch [0.

In the form shown in Fig. 6 the two knives l2 and I3 are similar in form and size and each is provided with a single notch M at its cutting edge, and it is seen that the knives are held in relation to each other in such a way that each overlaps the other on the two ends. Such knives I 2 and I3 must be used with greater care than those above described in that their position relatively to each other, or the extent that one overlaps the other, will govern the size of the patch.

It will also be understood that the patch cut from the strip by the downward motion of the knives I and 2 stays between them and is pushed upward by the successive patches being cut from the strips as they pass. The patches have their slivers [0 out soon after they travel upward in the space between the knives, by means of the sharpened edges ll of the notches 9. Since the space 6 increases in size towards the top of the knives the patches travel upward therein easily.

Thus it will be seen that the tool for cutting out the patch from the strip, comprises two similar curved knives which spring apart when hit with a hammer, when used as a hand tool, thereby cutting the patch with beveled edges.

It is of course understood that many variations may be made in the details of construction of the above-described machine, without departing from the spirit of my invention as outlined in the appended claims.

Having, therefore, described my invention what I claim and desire to secure by Letters Patent, is:

1. A patch cutting tool, comprising a pair of similarly curved complementary knives, contacting with each other to enclose an open space, the vertical end of one knife contacting with the vertical side wall of the other knife, whereby the ciu-ved line of shear of one knife completely crosses the oppositely curved line of shear extended of the other knife.

2. A patch-cutting tool as set forth in claim 1, wherein said complementary knives are each made on continuous arcuate curves of equal radii.

3. A patch-cutting tool, as set forth in claim 1, wherein said complementary knives are each made on continuous arcuate curves of equal radii, and wherein the one subtends a greater angle than the other, whereby the space between the knives is wider at the top than at the bottom.

4. A patch-cutting tool, as set forth in claim 1, wherein said complementary knives are each made on continuous arcuate curves of equal radii, and wherein the angle subtended by each knife is greater at its upper end than at its cutting edge, whereby the space between the knives is wider at the top than at the bottom.

5. A patch-cutting tool, as set forth in claim 1, wherein the angle subtended by one knife is less than the angle subtended by the other and wherein said narrower knife is provided with notches at its cutting corners whereby they are out of contact at such corners, whereby the cutting edge of each knife may draw toward the other as the out is made and they are thereby permitted to cut a bevelled edge to said patch.

6. The method of cutting patches comprising loosely holding a pair of complementary inde pendent cutters so that their cutting edges lie in the same plane and out of contact with each other and their contacting edges lie in a plane substantially at right angles to said cutting plane, and applying a cutting force thereto.

7. The method of cutting patches as set forth in claim 6, consisting of resiliently holding said cutters in contact with each other.

EUGENE DUGAW. 

